refactor common settings logic for skills,agents (#17490)

Co-authored-by: ved015 <vedant.04.mahajan@gmail.com>
Co-authored-by: Tommaso Sciortino <sciortino@gmail.com>

packages/cli/src/utils/featureToggleUtils.ts

@@ -0,0 +1,185 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  SettingScope,
+  isLoadableSettingScope,
+  type LoadableSettingScope,
+  type LoadedSettings,
+} from '../config/settings.js';
+
+export interface ModifiedScope {
+  scope: SettingScope;
+  path: string;
+}
+
+export type FeatureActionStatus = 'success' | 'no-op' | 'error';
+
+export interface FeatureActionResult {
+  status: FeatureActionStatus;
+  featureName: string;
+  action: 'enable' | 'disable';
+  /** Scopes where the feature's state was actually changed. */
+  modifiedScopes: ModifiedScope[];
+  /** Scopes where the feature was already in the desired state. */
+  alreadyInStateScopes: ModifiedScope[];
+  /** Error message if status is 'error'. */
+  error?: string;
+}
+
+/**
+ * Strategy pattern to handle differences between feature types (e.g. skills vs agents).
+ */
+export interface FeatureToggleStrategy {
+  /**
+   * Checks if the feature needs to be enabled in the given scope.
+   * For skills (blacklist): returns true if in disabled list.
+   * For agents (whitelist): returns true if NOT explicitly enabled (false or undefined).
+   */
+  needsEnabling(
+    settings: LoadedSettings,
+    scope: LoadableSettingScope,
+    featureName: string,
+  ): boolean;
+
+  /**
+   * Applies the enable change to the settings object.
+   */
+  enable(
+    settings: LoadedSettings,
+    scope: LoadableSettingScope,
+    featureName: string,
+  ): void;
+
+  /**
+   * Checks if the feature is explicitly disabled in the given scope.
+   * For skills (blacklist): returns true if in disabled list.
+   * For agents (whitelist): returns true if explicitly set to false.
+   */
+  isExplicitlyDisabled(
+    settings: LoadedSettings,
+    scope: LoadableSettingScope,
+    featureName: string,
+  ): boolean;
+
+  /**
+   * Applies the disable change to the settings object.
+   */
+  disable(
+    settings: LoadedSettings,
+    scope: LoadableSettingScope,
+    featureName: string,
+  ): void;
+}
+
+/**
+ * Enables a feature by ensuring it is enabled in all writable scopes.
+ */
+export function enableFeature(
+  settings: LoadedSettings,
+  featureName: string,
+  strategy: FeatureToggleStrategy,
+): FeatureActionResult {
+  const writableScopes = [SettingScope.Workspace, SettingScope.User];
+  const foundInDisabledScopes: ModifiedScope[] = [];
+  const alreadyEnabledScopes: ModifiedScope[] = [];
+
+  for (const scope of writableScopes) {
+    if (isLoadableSettingScope(scope)) {
+      const scopePath = settings.forScope(scope).path;
+      if (strategy.needsEnabling(settings, scope, featureName)) {
+        foundInDisabledScopes.push({ scope, path: scopePath });
+      } else {
+        alreadyEnabledScopes.push({ scope, path: scopePath });
+      }
+    }
+  }
+
+  if (foundInDisabledScopes.length === 0) {
+    return {
+      status: 'no-op',
+      featureName,
+      action: 'enable',
+      modifiedScopes: [],
+      alreadyInStateScopes: alreadyEnabledScopes,
+    };
+  }
+
+  const modifiedScopes: ModifiedScope[] = [];
+  for (const { scope, path } of foundInDisabledScopes) {
+    if (isLoadableSettingScope(scope)) {
+      strategy.enable(settings, scope, featureName);
+      modifiedScopes.push({ scope, path });
+    }
+  }
+
+  return {
+    status: 'success',
+    featureName,
+    action: 'enable',
+    modifiedScopes,
+    alreadyInStateScopes: alreadyEnabledScopes,
+  };
+}
+
+/**
+ * Disables a feature in the specified scope.
+ */
+export function disableFeature(
+  settings: LoadedSettings,
+  featureName: string,
+  scope: SettingScope,
+  strategy: FeatureToggleStrategy,
+): FeatureActionResult {
+  if (!isLoadableSettingScope(scope)) {
+    return {
+      status: 'error',
+      featureName,
+      action: 'disable',
+      modifiedScopes: [],
+      alreadyInStateScopes: [],
+      error: `Invalid settings scope: ${scope}`,
+    };
+  }
+
+  const scopePath = settings.forScope(scope).path;
+
+  if (strategy.isExplicitlyDisabled(settings, scope, featureName)) {
+    return {
+      status: 'no-op',
+      featureName,
+      action: 'disable',
+      modifiedScopes: [],
+      alreadyInStateScopes: [{ scope, path: scopePath }],
+    };
+  }
+
+  // Check if it's already disabled in the other writable scope
+  const otherScope =
+    scope === SettingScope.Workspace
+      ? SettingScope.User
+      : SettingScope.Workspace;
+  const alreadyDisabledInOther: ModifiedScope[] = [];
+
+  if (isLoadableSettingScope(otherScope)) {
+    if (strategy.isExplicitlyDisabled(settings, otherScope, featureName)) {
+      alreadyDisabledInOther.push({
+        scope: otherScope,
+        path: settings.forScope(otherScope).path,
+      });
+    }
+  }
+
+  strategy.disable(settings, scope, featureName);
+
+  return {
+    status: 'success',
+    featureName,
+    action: 'disable',
+    modifiedScopes: [{ scope, path: scopePath }],
+    alreadyInStateScopes: alreadyDisabledInOther,
+  };
+}